Why can't the browser's DOM be used directly?

Directly manipulating the browser's DOM in modern frontend applications, especially in libraries like React, is undesirable for several reasons:

• Performance: Working with the real DOM is slower because changes trigger recalculations of styles, re-rendering, and reflow of elements on the page.
• Complexity of state management: When directly changing the DOM, it is difficult to track the current UI state and synchronize it with application data.
• Lack of optimizations: React uses a Virtual DOM — a lightweight copy of the real DOM, which allows efficiently calculating minimal changes and applying them all at once, reducing the number of operations on the real DOM.

Thus, the Virtual DOM acts as an intermediary that optimizes interface updates, improving performance and simplifying development.

Example: When the state of a React component changes, React first updates the Virtual DOM, compares it with the previous version (diffing), and then applies only the necessary changes to the real DOM.